On Sunday, the Bidens visited the coffin of Queen Elizabeth as it lies in state inside Westminster Hall in London.

Hundreds of thousands of people have filed past the late monarch's coffin since Wednesday. On Friday, the Queen's four children — King Charles, Princess Anne, Prince Andrew and Prince Edward — held a solemn vigil around their mother's coffin. On Saturday, the Queen's grandchildren — including Prince William and Prince Harry — did the same.

The Bidens also signed the official condolence book for Her Majesty at the historic Lancaster House near Buckingham Palace.

US President Joe Biden and First Lady Jill Biden pay their respects as they view the coffin of Queen Elizabeth II, as it Lies in State inside Westminster Hall, at the Palace of Westminster in London on September 18, 202

JOE GIDDENS/POOL/AFP via Getty Joe and Jill Biden

The U.S. president and first lady will join King Charles and other leaders, dignitaries and royals from around the world for a palace reception on Sunday evening.

US President Joe Biden and First Lady Jill Biden leave after paying their respects and viewing the coffin of Queen Elizabeth II, as it Lies in State inside Westminster Hall, at the Palace of Westminster in London on September 18, 2022

JACOB KING/POOL/AFP via Getty

On Thursday, the president and first lady visited the British Embassy in Washington, D.C., to pay tribute to the Queen and sign her condolence book."We mourn for all of you," Biden said at the embassy. "She was a great lady. I'm so delighted I got to meet her."

US President Joe Biden and First Lady Jill Biden pay their respects as they view the coffin of Queen Elizabeth II, as it Lies in State inside Westminster Hall, at the Palace of Westminster in London on September 18, 2022

JOE GIDDENS/POOL/AFP via Getty President Joe Biden and First Lady Jill Biden

Following the Queen's death, the couple said in a statement, part: "We send our deepest condolences to the Royal Family, who are not only mourning their Queen, but their dear mother, grandmother, and great-grandmother. Her legacy will loom large in the pages of British history, and in the story of our world."

king charles

YUI MOK/POOL/AFP via Getty King Charles

The Bidens will be the only U.S. delegates in attendance at Monday's funeral.

In the past, former U.S. presidents have also been in attendance for significant historical events such as this, leading some to wonder why the White House wasn't provided with an open invitation to corral other U.S. figureheads.